Oven heating system



' variety easily obtainable inthe heteotcd May 112,, ices messesasses-so overs isssrmo srsrsrs ltco Machete, Son-l rohcisco, .Joliil'flll Elsie.

My invention relates to a, system for heating ovens, and moreparticularly to a means for utilising electricity to maintain the heat,in an oven. preheateai by gas.

The main object of my invention is to provide an oven which may hepreheated by gas and maintained in temperature by electricity.

Another object of my invention is to provide a simple and eilicientmeans for maintaining the temperature of an oven preheated by gas, by anelectrical element of small current consumption.

ll still further object of my invention is to pro ville an oven heatingsystem which is ecohomicel for long time cooking.

Other objects of my invention will be apparent I or will he specificallypointed out in the descrip tion forming a part of this specification,out i. do not limit myself to the embodiment of the invention hereindescribed, as various forms may be eoloptecl within the scope of theclaim.

My invention may he more fully understood direct reference to thedrawing, which is a groin showing one preferred form of the heat .,4system embodying my invention.

El cooking oven, as indicated by the broken line i, is provided with theusual gas burner 2, supplied with gas through supply pipe 3, manualvalve 4 and solenoid valve 5. The ovenis also provided with an electricheating element 6 which is of small wattage, not sufficient to requireany special wiring, and which can be plugged into any existing serviceoutlet nearby.

Current leads '5 from the electric heater lead to the A. G. mains 8, endin series with the heating element is a thermostat 3 within the oven. l.Also placecl in series with the heater and. thermostat is a solenoidswitch it. A time clock ii electrically controls both solenoid valve inthe gesline and solenoid switch it in series with the electric element.The time clock is oi the usual trade for turning on or various circuits,as e terminecl by'the setting of timing dials and The clockv mayelectrically driven by connection it from the males 3.

In operation, solenoid valve 5 is normally open, es is solenoid switchiii. The manual valve s in the gas burner is opened and the gels corneris lighted. After a predetermiheo time has elapsed, in accordance withthe desired preheating tem perature of the oven, the clock l l operates,shut ting oil the gas by closing solenoid valve sud energizing theelectric heating element 5 by closing solenoid switch The cooking theythen he continued under heat from the electric hecting element ii only,the temperature of cooking to he maintained regulated by the thermostat9. if desired, the time clock. M can he utilized to open solehoiciswitch such time as desirecl following predetermined time schedules forcooking different articles oi ioocl.

item thus chic, by operating the oven in the above described manner, toobtain fast preheating of the oven icy moors of the gas burner, antithen to maintain prolonged cooking at the tem- ,oerature attained duringpreheating, by means of electric heater l. The use oi the latter, clueto the that only e. smell amount oi' heat is required to maintaintemperature in the even, gives rise to economy oi oveh operation whichcannot he obtained by the use of either gas or electricity clone.

Furthermore, it is well know that gee homers do not function well when toeti very low end. are always in danger of being clot/h. o Whereas themaintaining temperature cc he Erect up by the low powered heatingelement.

It will also he obvious to those slzillecl in the art that the timeclock may be entirely eliminated and a second thermostat substitutedtherefor. This auxiliary thermostat may he placed within the oven, analwhen the oven. reaches a certain predetermined temperature thethermostat action can be utilised to close the solenoid valve 5 and toclose the solenoid switch es describes ahove for the cloclt.

I claim:

In combination with. cooking oven, e. gas

burner and oh heating eleihert ssid oven, means for supplying" gas tosaid cu ier, saici burner having o, large heating capacity quick- 1yraising seio". oven and contents thereof to desirecl cooking t otiherture, said; electric heat ing element having Gl'llff suiflicient heatingcapacity to supply soiti oven with slightly more heat than necessary tomaintain it at saiti cooking temperature when. attained, an electriccircuit for supplying current to said electric heating element, athermostat responsive to oven temperature for controlling said circuit,a time clock, :meens controlled by said time clock for shutting off:said our-her after a predetermined period; of operation andsimultaneously placing said electric heating element under control ofsaid; thermostat.

LEO S. MADLEM.

